California Code, Probate Code - PROB § 2108

(a) Except to the extent the court for good cause determines otherwise, if a guardian of the person is nominated as provided in Article 1 (commencing with Section 1500) of Chapter 1 of Part 2 and is appointed by the court, the guardian shall be granted in the order of appointment, to the extent provided in the nomination, the same authority with respect to the person of the ward as a parent having legal custody of a child and may exercise such authority without notice, hearing, or court authorization, instructions, approval, or confirmation in the same manner as if such authority were exercised by a parent having legal custody of a child.

(b) Except to the extent the court for good cause determines otherwise and subject to Sections 2593, 2594, and 2595, if a guardian of the estate is nominated under Section 1500 or a guardian for property is nominated under Section 1501 and the guardian is appointed by the court, the guardian shall be granted in the order of appointment, to the extent provided in the nomination, the right to exercise any one or more of the powers listed in Section 2591 without notice, hearing, or court authorization, instructions, approval, or confirmation in the same manner as if such authority were granted by order of the court under Section 2590.  In the case of a guardian nominated under Section 1501, such additional authority shall be limited to the property covered by the nomination.

(c) The terms of any order made under this section shall be included in the letters.